June 2023
Volume 64, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2023
NOS Expression in Chick Ocular Tissues in Response to Myopic Defocus
Author Affiliations & Notes
  • Jody A Summers
    Cell Biology, University of Oklahoma Health Science Center, Oklahoma City, Oklahoma, United States
  • Diana Soriano
    Cell Biology, University of Oklahoma Health Science Center, Oklahoma City, Oklahoma, United States
  • Footnotes
    Commercial Relationships   Jody Summers None; Diana Soriano None
  • Footnotes
    Support  NIH Grant EY009391
Investigative Ophthalmology & Visual Science June 2023, Vol.64, 835. doi:
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      Jody A Summers, Diana Soriano; NOS Expression in Chick Ocular Tissues in Response to Myopic Defocus. Invest. Ophthalmol. Vis. Sci. 2023;64(8):835.

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      © ARVO (1962-2015); The Authors (2016-present)

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Purpose : Considerable evidence implicates the gaseous neurotransmitter, nitric oxide (NO), in the control of postnatal eye growth and emmetropization. Inhibition of NO synthesis transiently disinhibits ocular growth during recovery from induced myopia, while administration of L-arginine (a substrate for NO synthesis) inhibits myopia development. Moreover, NO has been shown to mediate the ocular growth-inhibitory effects of atropine and dopamine receptor agonists. In an effort to identify the ocular tissue(s) responsible for NO synthesis during emmetropization, we compared the expression of the three NO-synthesizing enzymes [NOS1 (nNOS), NOS2 (iNOS), and NOS3 (eNOS)] in chick ocular tissues in two models of emmetropization: recovery from form deprivation myopia and compensation for +15D lenses. We hypothesize that myopic defocus (imposed during recovery or following +15D lens treatment) is associated with increased NOS 1, 2 or 3 expression in one or more ocular tissues.

Methods : Ocular tissues were harvested from control and treated eyes of chicks following 24 hrs of +15D lens wear, or following 5 hrs of recovery from 10 days of form deprivation-induced myopia. Gene expression of NOS1, NOS2 and NOS3 was quantified using Taqman™ real time PCR and normalized to the housekeeping gene, GAPDH.

Results : We compared gene expression of the three NOS isoforms in the retina, RPE, and choroid. Results and statistics are summarized in the table below. No significant differences were detected in NOS1 and NOS2 in the retinas of +15D lens-treated or recovering eyes, compared with controls (NOS3 was undetectable). NOS2 was significantly increased in the RPE of +15D lens-treated eyes. No significant differences were detected in NOS1 or NOS3 expression in the RPE of +15D lens-treated eyes, and no statistically significant differences were detected in NOS1, NOS2 or NOS3 in RPE of recovering eyes. NOS1, NOS2 and NOS3 were all significantly decreased in choroids of recovering and +15D lens-treated eyes, compared with controls.

Conclusions : Although the chick choroid contains several cell types that can synthesize NO, our results suggest that the choroid is not the source of NO that is involved in the slowing of ocular growth during emmetropization. Instead, we suspect that the RPE may be a major site of NO synthesis in response to myopic defocus, via increased NOS2 expression.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.



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